Certain pesticidal agents are inactivated by ultraviolet radiation from the sun. Because those pesticidal agents are useful for the control of undesirable pests and are applied in areas where they will be exposed to ultraviolet radiation, there is a need for photostable compositions containing those agents.
To prevent ultraviolet inactivation of pesticidal agents, compositions have been prepared which contain ultraviolet absorbers and/or reflectors and a pesticidal agent.
U.S. Pat. No. 3,541,203 describes a protected virus composition for insect control. The preferred composition includes a virus, an actinic light absorbing material and a polymeric binder material. The patent discloses that to bind the admixture of an actinic light absorbing material and a virus together with an ethylcellulose polymeric material, the admixture is combined with an ethylcellulose in toluene solution. The resultant mixture is agitated, treated with polybutadiene and poured into petroleum distillate which causes the ethylcellulose to solidify to yield very small particles of ethylcellulose polymeric material having substantially homogeneously enclosed within the particles the admixture of the actinic light absorbing material and the virus. The particles are then washed several times with additional petroleum distillate to completely remove residual amounts of the liquid polybutadiene material. Unfortunately, the process used to prepare the preferred compositions of U.S. Pat. No. 3,541,203 is not entirely satisfactory because it requires the use of toxic materials and numerous washing steps with flammable solvents.
U.S. Pat. No. 4,948,586 discloses a microencapsulated insecticidal pathogen. Four microencapsulated compositions are shown to decrease the photoinactivation of Autographa californica NPV. However, the microencapsulated compositions only retained from 30.7 to 71.43% of the original activity before being exposed to sunlight. U.S. Pat. No. 4,948,586 discloses a method of preparing microencapsulated insecticidal pathogens which has numerous steps and is both time consuming and laborious. It is apparent that neither the process nor the microencapsulated insecticidal pathogens described in U.S. Pat. No. 4,948,586 are entirely satisfactory for protecting insecticidal pathogens from the effects of ultraviolet radiation.
It is an object of the present invention to provide a coated pesticidal agent which retains a significant amount of its original activity after exposure to ultraviolet radiation.
It is also an object of the present invention to provide simple, less arduous processes for the preparation of coated pesticidal agents which are more suitable for commercial manufacture.
It is a further object of the present invention to provide a wettable powder pesticidal composition containing a coated pesticidal agent.